Image receiving medium

ABSTRACT

PCT No. PCT/JP89/00930 Sec. 371 Date May 14, 1990 Sec. 102(e) Date May 14, 1990 PCT Filed Sep. 12, 1989 PCT Pub. No. WO90/02660 PCT Pub. Date Mar. 22, 1990.The image receiving medium of the present invention is an image receiving medium to be used in combination with a heat transfer sheet, characterized in that the image receiving medium includes a laminate of at least one polyvinyl chloride resin sheet, and at least a layer of the image receiving medium superposed on the heat transfer sheet which receives the dye from the heat transfer sheet includes a polyvinyl chloride resin composition containing 0.1 to 10 parts by weight of a plasticizer based on 100 parts by weight of the polyvinyl chloride resin. The image receiving medium of the present invention has specific features in that no image receiving layer is required to be provided separately, image formation of a picture and the like according to the heat transfer system can be effected sharply and quickly, and yet curling caused by heat transfer is not generated.

This is a continuation of application Ser. No. 07/490,590 filed May 14,1990, now abandoned.

TECHNICAL FIELD

This invention relates to a recording material, more particularly to animage receiving medium made of a polyvinyl chloride which can formeasily and sharply a complicated image such as a picture of a face, andthe like, to be formed on an ID card according to a heat transfersystem.

BACKGROUND ART

In the prior art, many cards such as identification certificates,driving licenses, membership cards, etc. have been used, and on thesecards is recorded various information for clarifying identification, andthe like, of the owner. Particularly, on ID cards, and the like, a facephotograph is the most important feature.

A classical method for imparting face photographs on to various cards isa method of securing a face photograph to a predetermined portion of acard substrate by use of an adhesive, but this method is very cumbersomein its operation, and also has the drawback that unevenness is createdon the card surface.

Whereas, in the prior art, there has been developed an image formingmethod according to the sublimation transfer method. The sublimationtransfer method is a method in which a sublimation transfer sheet,having a layer containing a dye which is sublimation transferred by heaton the surface of a substrate film and an image receiving sheet aresuperposed, and a desired image is formed on the image receiving sheetby heating with a thermal head according to an image information fromthe back of the sublimation transfer sheet, and there is the advantagethat it can be practiced by a simple heat transfer printer.

Whereas, when the sublimation transfer system is applied to a cardmedium such as an ID card, the card substrate is demanded to havesufficient dyeability for a sublimable dye. However, most of the cardsubstrates of the prior art have no sufficient dyeability for sublimabledyes, and therefore no image formation can be effected thereon as such.As the method for solving such drawback, a method of previously formingan image receiving layer excellent in dyeability for a sublimable dyemay be conceivable, but formation of such image receiving layer on acard substrate is cumbersome in steps, whereby there is the problem ofincreasing the production cost of the card substrate. Further, when animage receiving layer is provided separately on the surface of a cardsubstrate, there will ensue such problems that the card substrate may becurled or the image receiving layer may be peeled off as caused by theheat applied during image formation.

DISCLOSURE OF THE INVENTION

The present invention has been accomplished in view of the problems ofthe prior art as described above, and its object is to provide an imagereceiving medium which is not required to provide separately an imagereceiving layer on a card substrate, can effect image formation of aface photograph according to the heat transfer system sharply andquickly, and yet generates no curls which otherwise tend to be caused byheat transfer printing.

For accomplishing the object as mentioned above, the image receivingmedium is an image receiving medium to be used in combination with aheat transfer sheet, characterized in that the image receiving mediumcomprises a laminate of at least one polyvinyl chloride resin sheets,and at least a layer of the image receiving medium superposed on theheat transfer sheet which receives the dye from the heat transfer sheetcomprises a polyvinyl chloride resin composition containing 0.1 to 10parts by weight of a plasticizer based on 100 parts by weight of thepolyvinyl chloride resin.

The image receiving medium of the present invention uses a polyvinylchloride vinyl resin as the main agent, and yet a plasticizer isincorporated in the main agent and its amount contained is made to becontrolled strictly, and therefore an image receiving medium excellentin both image forming characteristic and image quality is obtained alsowithout requiring separate formation of an image receiving layer.

Particularly, in the present invention, by making the structure of theimage receiving medium a symmetrcal laminate structure of three layers,the problem of curl which is liable to be generated in the heat transfersystem can be effectively prevented.

Further, in the present invention, by controlling strictly the softeningtemperature of the image receiving surface of the image receiving mediumwithin a specific range, further improvement of printing characteristiccan be effected.

Still further, in the image receiving medium of the present invention,the image quality can be made further excellent by containing no pigmentin the image receiving surface of the image receiving medium at all,thus having a specific feature also in this point.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, FIG. 2, FIG. 3, FIG. 5 AND FIG. 6 are respectively sectionalviews showing the constitution of the image receiving medium accordingto Examples of the present invention, and FIG. 4 is a sectional view ofa protective layer transfer sheet.

BEST MODES FOR PRACTICING THE INVENTION

In the following, the present invention is described in more detail byreferring to preferred embodiments.

The polyvinyl chloride resin to be used in the present invention may beknown per se.

In the present invention, in forming an image receiving medium frompolyvinyl chloride, at least as the layer constituting the imagereceiving layer, an image receiving medium is molded by using oneincluding 0.1 to 10 parts by weight of a plasticizer per 100 parts byweight of polyvinyl chloride. By this, the image receiving mediumexhibits sufficiently good dyeability of a sublimable dye.

As the plasticizer to be used in the present invention, phthalateplasticizers, phosphate plasticizers, aliphatic dibasic acid esterplasticizers, epoxy plasticizers, polyester plasticizers, chlorinatedparaffins, etc. can be used. Specifically, plasticizers known in theprior art can be preferably used, including dibutyl phthalate,di-n-octyl phthalate, di-(2-ethylhexyl) phthalate, dinonyl phthalate,dilauryl phthalate, butyl lauryl phthalate, butyl benzyl phthalate,di-(2-ethylhexyl) adipate, di-(2-ethylhexyl) sebacate, tricresylphosphate, tri-(2-ethylhexyl) phosphate, triethylene glycol ester,tetraethylene glycol ester, epoxy fatty acid ester, etc.

The amount of these plasticizers used may be 0.1 to 10 parts by weightper 100 parts by weight of the above-mentioned polyvinyl chloride, and aparticularly preferable range is from 3 to 5 parts by weight. It isnecessary to control strictly the amount of the plasticizer used, andwith an amount less than 0.1 part by weight, dyeability onto asublimable dye is insufficient, while if it exceeds 10 parts by weight,the card material lacks rigidity to become soft, whereby the dye layerof the sublimation type heat transfer sheet may be used during heattransfer to make the card substrate and the heat transfer sheetunpeelable, or abnormal transfer such as peel-off of the dye layer fromthe heat transfer may occur. Also, blurring occurs on the printed imageduring sublimation transfer thus precluding sharp image formation.

Also, in the preferred embodiment of the present invention, when 0.1 to5 parts by weight of a lubricant per 100 parts by weight of polyvinylchloride are included in addition to the above-described plasticizer, nobad influence will appear even if the plasticizer may be included inpolyvinyl chloride in a relatively larger amount, for example, at aratio of 5 to 10 parts by weight, but on the contrary it has beenconfirmed that printing characteristics are improved. More specifically,the present inventor has found that blocking of the transfer sheetduring transfer is prevented, and yet dyeability with the sublimable dyeof the image receiving medium obtained is further improved by suchcomplex addition.

As such lubricant, all of the lubricants known in the art such as fattyacids, fatty acid amides, waxes, paraffins, etc. can be used. If theamount of these lubricants used is too small, there is no advantage byaddition, while if it is too much, the surface roughening of the imagereceiving medium obtained will undesirably occur. Also, by use of theselubricants, not only dyeability of a sublimable dye can be improved, butalso adhesion between the heat transfer sheet and the image receivingmedium is little even by use of a relatively higher temperature duringsublimation transfer, whereby an image of higher density can be formedefficiently.

The main components constituting the image receiving medium have been asdescribed above, but of course in the present invention, coloredpigments, white pigments, extender pigments, fillers, UV-absorbers,antistatic agents, heat stabilizers, antioxidants, fluorescentbrighteners, etc. can also be used additionally.

The image receiving medium of the present invention is obtained byblending the necessary components as described above, and molding theblended product by the formation method known in the art such as thecalendering method, the extrusion method, etc. into a sheet with athickness of, for example, about 0.05 to 1 mm, and the present inventionis inclusive of both the sheet before cut into the so called card sizeand those cut into the card size.

FIG. 1 and FIG. 2 are sectional views of the basic mode of the imagereceiving medium of the present invention, and this is shaped in a sheetwith a thickness of about 0.1 to 1 mm. By superposing a knownsublimation type heat transfer sheet A with the dye layer 2 opposed ontothe surface of the image receiving member 1 and heating with a thermalhead 3 from the back of the sublimation transfer sheet A, a desiredimage 4 is formed on the surface of the image receiving medium 1. Ofcourse, such image receiving medium 1 may also have an embossed pattern5 or another printing pattern 6 previously formed thereon, and also,these emboss 5 and printing pattern 6 may be provided after sublimationtransfer, and further a transparent protective layer 7 may be formed onthe whole surface or a part of its surface for improvement of durabilityof these images.

An example shown in FIG. 3 shows a sectional view of the image receivingmedium of another preferred embodiment of the present invention. Theimage receiving medium 11 of this example has oversheets (transparentpolyvinyl chloride layers) 13 laminated on both surfaces of a centercore 12 containing a white pigment (for example, a white rigid polyvinylchloride resin having a thickness of 0.1 to 0.8 mm, etc.). At least oneof the oversheets 13 contains a specific amount of a plasticizer (and alubricant) as described above. In this example, the center core 12 isnot necessarily required to contain a predetermined amount ofplasticizer, and the oversheets 13 on its surfaces have sufficientdyeability similarly as described above. In this example, on thesurfaces of the center core 12, various printed patterns 14 can bepreviously formed.

As described above, formation of the structure into a symmetricallaminate structure of three layers is very effective in preventingeffectively the problem of curl which is liable to be generated duringheat transfer in the prior art. Also, by forming the dye receivingsurface of a transparent polyvinyl chloride resin, the depth, the cubicfeeling of image are good, and further since the dye receiving layercontains no pigment, luster is good and also coarseness on the printedsurface is little.

Further, the image receiving medium of the present invention can alsohave other recordings, such as magnetic recording layer, writing layer,IC memory, bar code, etc. previously provided on its surface.

Also, in the present invention, by restricting the soft temperature(according to the standard defined in JIS-K-6734) of the above-mentionedpolyvinyl chloride composition constituting the image receiving mediumstrictly within the range of from 50° to 70° C., printingcharacteristics, particularly operability, dye dyeability and blurringprevention of an image in heat transfer by use of a thermal head can beimproved, and further one with good emboss characteristics (formationcharacteristic of embossed letters) can be obtained.

In this case, at a soft temperature lower than 50° C., abnormal transferfrequently occurs, and also blurring of image after printing isincreased, while if the soft temperature exceeds 70° C., dye dyeabilitywill be lowered undesirably markedly. Besides, if the soft temperatureexceeds 70° C., it becomes difficult to form good embossed letters, andfine cracks may be formed at the embossed portion unsuitably.

The image receiving medium in the present invention may also contain anantistatic agent, or an antistatic agent may be also coated on thesurface. As the antistatic agent, there can be employed cationicsurfactants (e.g. quaternary ammonium salts, polyamine derivatives,etc.), anionic surfactants (e.g. alkylphosphates, etc.), amphotericsurfactants (e.g. those of the betaine type, etc.) or nonionicsurfactants (e.g. fatty acid esters, etc.), and further those of thepolysiloxane type. By coating or incorporating these antistatic agents,conveying troubles by static charges during printing of the dyereceiving member in sheet can be cancelled, and also when the dyereceiving medium has a magnetic recording layer or an IC memory,electrostatic breaking of memory contents can be prevented. A preferablerange of surface resistance value from such point of views may be 10⁸ to10¹² Ω/cm². For imparting IC memory, optical memory, known techniques,such as those described in Japanese Laid-Open Patent Application No.61-103287 can be applied.

Image formation

Generally speaking, heat transfer sheets may be classified broadly heattransfer sheets of the so called melt ink transfer type of which heattransfer layers are melted or softened by heating to be heat transferredimagewise onto a heat transferable material, and heat transfer sheets ofthe so called sublimation dye transfer type of which the dyes in theheat transfer layer are sublimated (heat migrated) by heating to haveonly the dyes heat transferred onto a heat transferable material.

When ID cards such as identification certificates and the like are to beprepared with such heat transfer sheets as described above, in the caseof heat transfer sheets of the melt ink transfer type, formation ofmonotonous images such as letters, figures, etc. can be done easily, butthere is the problem that formation of gradation image such as facephotograph can be done only with difficulty. On the contrary, in thecase of heat transfer sheets of the sublimation transfer type, althoughgradation image of face photograph, etc. is excellent, images such asletters, symbols, etc. are deficient in density and sharpness, and noOCR letter, bar code, etc. readable with IR-ray can be formed. Thus,none of the sheets can form satisfactory images.

As the method for solving such drawbacks, the method which employsprinting with the above-mentioned fusion type (melt type) transfer andprinting with the sublimation type transfer sheet in combination ispreferred.

The ink for formation of heat meltable ink layer to be used in the abovemethod comprises a colorant and a vehicle, and may further containvarious additives added therein, if desired.

As the colorant as mentioned above, of organic or inorganic pigments ordyes, those having good characteristics as the recording material, forexample, having sufficient coloration density without discoloration orfading by light, heat, temperature, etc. are preferred. As the colorant,cyan, magenta, yellow, etc. may be also used, but for the purpose of thepresent invention, colorants of black which can print clear letters andsymbols at high density are preferred.

As the vehicle, one comprising a wax as the main component, andotherwise mixtures of a wax with drying fat, resin, mineral oil,derivatives of cellulose and rubber, etc. may be employed.

Representative examples of wax may include microcrystalline wax,carunauba wax, paraffin wax, etc. Further, there may be employed variouswaxes such as Fischer-Tropsh wax, various low molecular weightpolyethylenes, wood wax, beeswax, whale wax, insect wax, wool wax,shellac wax, canderilla wax, petrolatum, partially modified wax, fattyacid ester, fatty acid amide, etc. However, from the standpoint ofadhesion to vinyl chloride resin, scratch resistance, the black inkshould more preferably use a resin binder as shown below:

(1) Acrylic resin,

(2) Acrylic resin+Chlorinated rubber,

(3) Acrylic resin+Vinyl chloride/Vinyl acetate copolymer resin,

(4) Acrylic resin+Cellulose type resin,

(5) Vinyl chloride/vinyl acetate copolymer resin.

As the method for forming a heat meltable ink layer on a substrate filmor a release layer previously provided thereon, there may be included,in addition to hot melt coating, the methods of coating the above inkaccording to many means such as hot lacker coating, gravure coating,gravure reverse coating, roll coating and others. The thickness of theink layer formed should be determined so that the necessary density andthe heat sensitivity can be matched and, for example, the thickness ofthe ink layer should be generally preferably within the range of fromabout 0.2 to 10 μm.

Prior to formation of the heat meltable ink layer as mentioned above, itis preferable to form a release layer on the surface of the substratefor making peeling of the heat meltable ink layer easier. Such releaselayer is formed of a peeling agent such as waxes, silicone waxes,silicone resin, fluorine resins, acrylic resins, cellulose resins, vinylchloride/vinyl acetate copolymer resins, nitrocellulose resins, etc. Theformation method may be the same as the formation method of theabovedescribed sublimable dye layer and the heat meltable ink layer, andits thickness may be sufficiently about 0.1 to 5 μm. When matte printingor matte protective after transfer is desirable, various particles canbe included in the release layer to make the surface matte.

Next, the sublimation type heat transfer sheet is to be described.

First, as the substrate film of the heat transfer sheet, the samesubstrate films which have been used in the heat transfer sheet of theprior art can be used as such, and also other films can be used, and arenot particularly limited.

As specific examples of preferable substrates, for example, thin paperssuch as glassine paper, condenser paper, paraffin paper, etc. areuseful, and otherwise there may be included plastics such as polyester,polypropylene, Cellophane, polycarbonate, cellulose acetate,polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide,polyvinylidene chloride, ionomer, etc. or substrate films comprisingcomposite materials of these with the above-mentioned papers.

The thickness of such substrate film can be suitably varied so that itsstrength and heat resistance, etc. may become adequate, but itsthickness should be preferably 3 to 100 μm.

The dye layer of the heat transfer sheet is a layer having a sublimabledye carried on the substrate film as described above with any desiredbinder.

As the dye to be used, all of the dyes used for heat transfer films ofthe sublimation type known in the prior art are effectively available,and not particularly limited. For example, as some preferable dyes,there may be included, as red dyes, MS Red G, Macrolex Red Violet R,Ceres Red 7B, Samaron Red HBSL, SK Rubin SEGL, etc., also as yellowdyes, Phorone Brilliant Yellow, S-6GL, PTY-52, Macrolex Yellow S-6G,etc., and also as blue dyes, Kayaset Blue 714, Waxsoline Blue AP-FW,Phorone Brilliant Blue S-R, MS Blue 100, Dito Blue No. 1, etc.

As the binder for carrying the dye as mentioned above, all of thoseknown in the prior art can be used, and preferable examples may includecellulose type resins such as ethyl cellulose, hydroxyl cellulose,ethylhydroxy cellulose, hydroxypropyl cellulose, methyl cellulose,cellulose acetate, cellulose acetate butyrate, etc.; vinyl resins suchas polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinylacetal, polyvinyl pyrrolidone, polyacrylamide, etc., but particularlypolyvinyl acetal and polyvinyl butyral, etc. are preferable from suchpoints as heat resistance, heat migratability of dye, etc.

The dye layer is formed basically of the materials as described above,but otherwise various additives known in the prior art can be alsoincluded, if necessary.

Such dye layer is formed preferably by preparing an ink for dye layerformation by dissolving or dispersing the respective components of theabove-mentioned dye, binder resin and other optional components into anappropriate solvent, and printing and drying the ink on theabove-mentioned substrate film according to the gravure printing method,etc. Of course, although monochromatic printing may be employed incarrying out such printing, for the purpose of the present invention, amulti-color printing of three colors of yellow, magenta and cyan or fourcolors with addition of black is preferable so that a color image can beformed.

Formation of protective layer

As described above, in the case of image formation of sublimation type,gradation image such as face photograph, etc. can be formed, but theformed image lacks luster due to absence of vehicle as different fromconventional printing ink, and also for the same reason, there is theproblem that it is inferior in durability such as friction resistance.

As the method for solving such problem, there is the method oflaminating a transparent film on the image surface formed. However, thismethod is cumbersome in operation, and also since lamination is effectedon the card as a whole, curl may occur on the card, and further no toothin film can be used in operation of the card, and therefore there isthe problem that the card laminated becomes thick as a whole.

The above problem can be solved by forming a protective layer by use ofa sheet for protective layer transfer as described below.

The sheet for protective layer transfer to be used in this method ischaracterized by providing releasably a protective layer releaseprotective layer comprising a wax-containing transparent resin and aheat seal layer to be fusion transferred by heat onto the vinyl chlorideresin on a substrate film.

When transfer of the protective layer is effected onto the surface ofthe image by use of the above-mentioned sheet, the protective layer istransferred easily onto the image by the heat during printing, andtherefore an excellent printed matter excellent in durability,particularly friction resistance, luster, color formability, etc. andwithout generation of curl can be obtained by a simple operation.

FIG. 4 shows diagrammatically a sectional view of the protective layertransfer sheet according to a preferable example. The protective layertransfer sheet of this example has a release protective layer 43comprising a wax-containing transparent resin provided releasablythrough an adhesion improving layer 42 on the substrate film 41.

In the Figure, 42 is an adhesion improving layer, which has the actionof making better peel-off of the protective layer by improvement of theadhesion between the release protective layer and the substrate film. Ifadhesion between the release protective layer and the substrate film ispoor, the portions other than the heating portion of the protectivelayer will be released together with the heating portion duringtransfer, whereby peel-off is worsened.

45 is a heat-resistant lubricating layer, which has the action ofpreventing sticking of the thermal head of a printer. The layer 45 isnot required, when heating resistance and slipping characteristic of thesubstrate film are good.

As the above substrate film 41, the same substrate films as used in theheat transfer films of the prior art can be used as such, and also otherfilms can be used and are not particularly limited.

As specific examples of the substrate film 41, for example, thin paperssuch as glassine paper, condenser paper, paraffin paper, etc. areuseful, and otherwise there may be included plastics such as polyester,polypropylene, Cellophane, polycarbonate, cellulose acetate,polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide,polyvinylidene chloride, ionomer, etc. or substrate films comprisingcomposite materials of these with the above-mentioned papers.

The thickness of such substrate film 41 can be suitably varied so thatits strength and heat resistance, etc. may become adequate, but itsthickness should be preferably 3 to 100 μm.

As the adhesion improving layer 42, it may be one which consolidatesadhesion between the substrate film and the release protective layer 43and, for example, polyester type resins, polyurethane type resins,acrylpolyol type resins, vinyl chloride-vinyl acetate copolymer typeresins, etc. may be used singly or as a mixture by coating. Also, ifnecessary, a reactive curing agent such as polyisocyanates, etc. may bealso added. Further, titanate and silane type coupling agents may bealso used. Also, two or more layers may be laminated, if necessary.

The release protective layer 43 is formed of a mixture of a transparentresin and a wax provided on the above-described adhesion improvinglayer.

As the transparent resin, there may be included polyester resins,polystyrene resins, acrylic resins, epoxy resins, modified celluloseresins, polyvinyl acetal resins, silicone resin, fluorine type resins,etc., preferably acrylic resins, silicone resins, fluorine resins. Theseresins are excellent in transparency, and form relatively toughcoatings. Also, film peel-off during transfer is good. However, becauselubricity is insufficient, damage is liable to be attached by surfacefriction.

In the present invention, lubricity of the protective layer is improvedby mixing a wax with these transparent resins.

Representative examples of wax may include microcrystalline wax,carunauba wax, paraffin wax, etc. Further, there may be employed variouswaxes such as Fischer-Tropsh wax, various low molecular weightpolyethylenes, wood wax, beeswax, whale wax, insect wax, wool wax,shellac wax, canderilla wax, petrolatum, partially modified wax, fattyacid ester, fatty acid amide, etc.

The amount of the above wax used may be preferably within the range offrom 0.5 to 20 parts by weight per 100 parts by weight of theabove-mentioned transparent resin, and if the amount of the wax used istoo small, friction resistance of the protective layer during formationof the protective layer becomes insufficient, while if it is too much,durability, transparency of the protective layer coating becomesundesirably insufficient.

The method of mixing the above-described transparent resin and wax mayinclude the method of melt mixing of both, the method of mixing bydissolving in an appropriate organic solvent capable of dissolving both,etc., and the mixing method is not particularly limited.

Particularly preferably, the transparent resin used as a dispersion (oremulsion), while the wax is used as a solution or a dispersion(emulsion), and the both are mixed together. After coating on thesubstrate film by use of such dispersions (emulsions), film formation iseffected at a relatively lower temperature so that at least a part ofthese resin particles may remain. The coating thus formed has a roughsurface because the resin particles remain to be partially turbid, butthe surface becomes smooth by heat and pressure during heat transfer,whereby it can be transferred as a transparent coating.

As the method for forming the releasable protective layer 43 on theadhesion improving layer 42 previously provided on the substrate film41, there may be included methods of coating and drying the inkcomprising the resin and the wax as described above according to manymeans such as gravure coating, gravure reverse coating, roll coating,etc. When the transparent resin layer is formed from a mixed dispersionof the resin and the wax, drying after coating should be preferablyconducted at a relatively lower temperature not higher than the meltingpoint of the resin particles, for example, about 50° to 100° C. Bydrying at such temperature, the film is formed with remaining of resinparticles, and therefore film peel-off during transfer is markedlyimproved to maintain lubricity of the transfer coating.

Also, substantially inorganic or organic fine particles can be mixed inthe release protective layer. By mixing fine particles, peel-off,abrasion resistance of the release protective layer can be furtherimproved. Also, a matte surface can be obtained by suppressing theluster of the surface.

As such fine particles, those with relatively higher transparency suchas silica, and Teflon powder, nylon powder, etc. are preferable. Theamount added may be preferably 1 to 30% by weight based on the resin ofthe release protective layer. In this case, if the amount added is toomuch, transparency of the protective layer, durability of the coatingwill be worsened.

The thickness of the release protective layer should be preferably 0.5to 5 μm.

Further, on the surface of the above-mentioned release protective layer,for the purpose of making better transferability onto the dye imagereceiving member comprising a vinyl chloride resin, a heat seal layer 44is provided. The heat seal layer is formed to a thickness preferably ofabout 0.5 to 10 μm by coating and drying a solution of a resin of goodhot adhesion such as acrylic resins, vinyl chloride resin, vinylchloride.vinyl acetate copolymer resins, acryl.vinyl chloride.vinylacetate copolymers, polyester resins, polyamide resins, etc.

Among these resins, those having good adhesion to vinyl chloride resinsand good peel-off are vinyl chloride.vinyl acetate copolymers,acryl.vinyl chloride.vinyl acetate copolymers, acrylic resins, polyamideresins.

Also, in forming the release protective layer and/or the heat seal layeras described above, by incorporating additives such as UV-ray absorbers,antioxidants, fluorescent brighteners, etc. in said layer, luster, lightresistance, weathering resistance, whiteness, etc. of various images tobe coated can be improved.

Having described above about the protective layer transfer sheetconstitution to be used in the present invention, the protective layerof such protective layer transfer sheet may be provided alone on thesubstrate film, or may be also provided in plane succession with thesublimation type dye layer and the melt transfer ink layer as a matterof course.

The images to be protected by use of the protective layer transfer sheetas described above are images according to the sublimation type heattransfer method and/or the melt ink type heat transfer method or barcodes which are letter informations, etc. on a dye receiving membercomprising a vinyl chloride resin, but they are not limited to these.Particularly when applied to a sublimation transfer image, a protectivelayer of said image is formed, and also the dye which forms the image bythe heat during transfer is subjected to the recolor formationtreatment, whereby there is the effect that the image becomes furthersharp.

The image receiving medium may be provided with emboss, sign, IC memory,optical memory, magnetic recording layer, other printings, etc., and itis also possible to provide emboss, sign, magnetic recording layer, etc.after the protective layer transfer. Also, by use of the card substrateof the present invention, emboss can be also applied on the facephotograph after image formation, which is very effective for preventingalteration of the card.

A preparation example of the transfer printed matter by use of the dyeimage receiving member, and the protective layer transfer sheet of thepresent invention as described above is described by referring to FIG.5, FIG. 6.

First, an image receiving medium 58 in the form of a card was prepared,having transparent vinyl chloride resins 57, 57' containing aplasticizer and a lubricant, but containing no colored pigment laminatedon both surfaces of a center core 56 comprising a vinyl chloride resincomprising a white pigment. On the surface of the image receivingmedium, a yellow dye layer for sublimation type heat transfer sheet wassuperposed, and a yellow image 59Y was transferred with a thermalprinter which actuates following color separation signal. Bytransferring similarly the magenta image 59M and the cyan image 59C ontothe same region, a desired color image 59 is formed. Next, by use of amelt ink type heat transfer sheet, desired letters, symbols, bar codes,etc. 58 are similarly printed. Further, by use of the protective layertransfer sheet as described above, the release protective layer and theheat seal layer on the above-mentioned color image 59 and/or the image60 such as letters, etc. to form a protective layer. Thus, a card havingformed desired information, images formed thereon can be formed.

In carrying out the transfer as described above, the thermal printersmay be separately set for sublimation transfer, for melt ink transfer,for protective layer transfer sheet (preferably continuously), oralternatively, these transfers may be effected by adequate control ofthe respective printing energies with the common printer. In the presentinvention, the means for heating the protective layer transfer sheet isnot limited to a thermal printer, but otherwise hot plates, hot rolls,iron, etc. may be also employed.

In the following, examples of the present invention are described inmore detail by referring to Examples and Comparative Examples. In thesentences, parts and % are based on weight, unless otherwiseparticularly noted.

EXAMPLES 1 TO 7 AND COMPARATIVE EXAMPLES 1 TO 3

According to the compositions shown below in Table 1, dye receivingsheets (white card substrates) (thickness 0.2 mm, size 10×20 cm) of thepresent invention and Comparative Examples were prepared.

                  TABLE 1                                                         ______________________________________                                                Components                                                                   PVC    Pigment  Plasticizer Lubricant                                  ______________________________________                                        Example 1                                                                              100      10       0.5       0.0                                      Example 2                                                                              100      10       1         0.0                                      Example 3                                                                              100      10       3         0.5                                      Example 4                                                                              100      10       5         1                                        Example 5                                                                              100      10       10        0.0                                      Example 6                                                                              100      10       10        3                                        Example 7                                                                              100      10       10        5                                        Comparative                                                                            100      10       0.0       0.0                                      Example 1                                                                     Comparative                                                                            100      10       15        0.0                                      Example 2                                                                     Comparative                                                                            100      10       20        0.0                                      Example 3                                                                     ______________________________________                                         PVC: polyvinyl chloride compound (polymerization degree 800) containing       about 10% of an additive such as stabilizer, etc.;                            Pigment: titanium oxide;                                                      Plasticizer: DOP (dioctyl phthalate);                                         Lubricant: stearic acid amide.                                           

Next, inks of three colors containing sublimable dyes of three colorshaving the compositions shown below respectively were prepared.

Yellow ink

    ______________________________________                                        Disperse dye (Macrolex Yellow 6G,                                                                       5.5 parts                                           Bayer, C.I. Disperse Yellow 201)                                              Polyvinyl butyral resin (Ethlec BX-1,                                                                   4.5 parts                                           Sekisui Kagaku K.K., Japan)                                                   Methyl ethyl ketone/toluene                                                                            89.0 parts                                           (weight ratio 1/1)                                                            ______________________________________                                    

Magenta ink

The same as yellow ink except for using a magenta disperse dye (C.I.Disperse Red 60) as the dye.

Cyan ink

The same as yellow ink except for using a cyan disperse dye (C.I.Solvent Blue 63) as the dye.

The above ink compositions were coated repeatedly according to thegravure coating method on the surface of a polyester film with athickness of 4.5 μm having a heat-resistant slip layer (thickness 1 μm)formed on the back, and an adhesion improving layer (thickness 0.5 μm)on the surface in plane succession in the order of yellow, magenta andcyan respectively at a width of 15 cm and dried to a coated amount ofabout 3 g/m², to form a heat transfer sheet containing sublimable dyelayers of three colors.

With the above sublimation type heat transfer sheet superposed on thesurface of the card substrate as previously described, heat energy wasimparted with a thermal head connected to the electrical signalsobtained by color separation of a face photograph to effect sublimationtransfer in the order of cyan, magenta and yellow, thereby forming aface photograph of full-color.

Next, on the surface of the same polyester film as described above, anink for release layer having the composition shown below was coatedaccording to the gravure coating method and dried at a ratio of 1 g/m²to form a release layer.

Ink for release layer

    ______________________________________                                        Acrylic resin           20 parts                                              Methyl ethyl ketone    100 parts                                              Toluene                100 parts                                              ______________________________________                                    

Next, on the surface of the above release layer was coated the ink shownbelow to a coated amount of about 3 g/m² and dried to form a heatmeltable ink layer to prepare a heat melt type heat transfer sheet.

Heat meltable ink

    ______________________________________                                        Acryl/vinyl chloride/vinyl acetate                                                                     20 parts                                             copolymer resin                                                               Carbon black             10 parts                                             Toluene                  35 parts                                             Methyl ethyl ketone      35 parts                                             ______________________________________                                    

On the image blank portion of the card having the above-mentioned facephotograph formed thereon, the melt ink type heat transfer sheet asdescribed above was superposed, and letters such as figures, Chinesecharacters, etc. and signal images such as bar code, etc. were formed.

The color formed density, sharpness of the face photograph and abnormaltransfer state of the heat transfer sheets during sublimation transferof the cards of the present invention and Comparative Examples wereexamined to obtain the results shown below in Table 2.

                  TABLE 2                                                         ______________________________________                                                Performance                                                                   Color formed       Abnormal transfer                                          density  Sharpness resistance                                         ______________________________________                                        Example 1 ◯                                                                            ◯                                                                           ◯                                  Example 2 ◯                                                                            ◯                                                                           ⊚                               Example 3 ⊚                                                                         ⊚                                                                        ⊚                               Example 4 ⊚                                                                         ⊚                                                                        ⊚                               Example 5 ⊚                                                                         ⊚                                                                        ◯                                  Example 6 ⊚                                                                         ⊚                                                                        ⊚                               Example 7 ⊚                                                                         ⊚                                                                        ⊚                               Comparative                                                                             X          X*.sup.1  X                                              Example 1                                                                     Comparative                                                                             ⊚                                                                         X*.sup.2  ⊚                               Example 2                                                                     Comparative                                                                             ⊚                                                                         X*.sup.2  ⊚                               Example 3                                                                     ______________________________________                                         *.sup.1 dye layer of heat transfer sheet transferred partially as such,       and resolution remarkably bad                                                 *.sup.2 blurring occurred on image, and resolution bad                   

The color formed density was compared with the naked eye, with thehighest density being represented by ⊚, moderate one by ◯, and inferiorone by x.

Sharpness was compared with naked eye, and the sharpest one wasrepresented by ⊚, moderate one by ◯ and inferior one by x.

Abnormal transfer resistance is represented by ⊚ when peeling of thetransfer sheet after sublimation transfer is easy, by ◯ when slightlydifficult, and x when peeling is difficult and the dye layer itself istransferred onto the card substrate.

EXAMPLES 8 TO 14 AND COMPARATIVE EXAMPLES 4 TO 6

A white card substrate core (thickness 0.2 mm, size 30×30 cm) wasprepared according to the composition shown below.

    ______________________________________                                        Polyvinyl chloride (polymerization                                                                   100 parts                                              degree 800) compound containing about                                         10% of additives such as stabilizer, etc.                                     White pigment (titanium oxide)                                                                        15 parts                                              ______________________________________                                    

Next, transparent sheets were prepared according to the compositionsshown below in Table 3 (thickness 0.15 mm), and thermally pressureadhered onto the both surfaces of the above white core to prepare cardsubstrates of Examples and Comparative Examples.

                  TABLE 3                                                         ______________________________________                                                Components                                                                   PVC    Pigment  Plasticizer Lubricant                                  ______________________________________                                        Example 8                                                                              100      --       0.5       0.0                                      Example 9                                                                              100      --       1         0.0                                      Example 10                                                                             100      --       3         0.5                                      Example 11                                                                             100      --       5         1                                        Example 12                                                                             100      --       10        0.0                                      Example 13                                                                             100      --       10        3                                        Example 14                                                                             100      --       10        5                                        Comparative                                                                            100      --       0.0       0.0                                      Example 4                                                                     Comparative                                                                            100      --       15        0.0                                      Example 5                                                                     Comparative                                                                            100      --       20        0.0                                      Example 6                                                                     ______________________________________                                    

When gradation images and monotonous images were formed on the surfaceof the above card substrates in the same manner as in Example 1 and thesame performances were examined, the same results as in Table 2 wereobtained.

EXAMPLES 15 TO 19 AND REFERENCE EXAMPLES 1, 2

For examination of the influence of the soft temperature (according tothe standard defined in JIS-K-6734) of the above polyvinyl chlorideresin compositions constituting the image receiving media, the followingtests were conducted.

First, on both surfaces of a center core with a thickness of 670 μmcomprising a vinyl chloride resin containing a white pigment werelaminated oversheets thickness 70-150 μm) comprising transparent vinylchloride resin compositions shown below, to form image receiving media.In this case, oversheets exhibiting those shown below in Table 4 as thesoft temperature of the oversheet were prepared. The soft temperaturewas controlled by controlling suitably the kinds and amounts ofplasticizers, lubricants, the molecular weights of PVC andcopolymerization with other resins, etc.

Example 1: "Vinifoil C-1436" (product of Mitsubishi Jushi, K. K, Japan)

Example 2: "Vinifoil C-0436" (product of Mitsubishi Jushi, K. K., Japan)

Example 3: "Vinifoil C-0446" (product of Mitsubishi Jushi, K. K., Japan)

Example 4 "Vinifoil C-4020" (product of Mitsubishi Jushi, K. K., Japan)

Reference Example 1: "Vinifoil C-850" (product of Mitsubishi Jushi, K.K., Japan)

Reference Example 2: "Hisilex 502" (product of Mitsubishi Jushi, K.K.,Japan).

For these sample media, presence of abnormal transfer, dye dyeability,blurring of image after printing, and emboss adaptability were tested.The results are shown below in Table 4.

                                      TABLE 4                                     __________________________________________________________________________                                          Reference                                                                           Reference                                 Example 15                                                                          Example 16                                                                          Example 17                                                                          Example 18                                                                          Example 19                                                                          Example 1                                                                           Example 2                         __________________________________________________________________________    Softening                                                                             66    65    62    60    57    85    45                                temperature °C.                                                        Abnormal                                                                              Virtually                                                                           Virtually                                                                           Virtually                                                                           none  none  "     "                                 transfer                                                                              none  none  none                                                      Dye     Common                                                                              Common                                                                              Good  Good  Good  No good                                                                             Good                              dyeability                                                                    Blurring of                                                                           none  none  none  none  none  Entirely                                                                            Generated                         image after                           none                                    printing                                                                      Emboss  Good  Good  Good  Good  Good  Unsuitable                                                                          Good                              adaptability                                                                  __________________________________________________________________________

EXAMPLES 20, 21 AND REFERENCE EXAMPLES 3 TO 5 EXAMPLE 20

On the other surface of a 4.5 μm PET film having a heat-resistantlubricating layer provided on one surface was provided a polyester typeadhesion improving layer (0.1 μm), and further a heat seal layer and apeelable protective layer having the compositions shown below weresuccessively coated according to the gravure coating method and dried toform a protective layer, thus preparing a protective layer transfersheet.

    ______________________________________                                        Releasable protective layer                                                   (coated amount after drying: 4 g/m.sup.2)                                     Acrylic resin          20     wt. parts                                       (Mitsubishi Rayon K.K., Japan:                                                BR-83)                                                                        Polyethylene wax       1      wt. part                                        Methyl ethyl ketone    50     wt. parts                                       Toluene                50     wt. parts                                       Heat seal layer                                                               (coated amount after drying: 1 g/m.sup.2)                                     Acryl.vinyl chloride.vinyl acetate                                                                   20     wt. parts                                       copolymer (Showa Ink K.K.,                                                    Japan: HS-32G)                                                                Methyl ethyl ketone    100    wt. parts                                       Toluene                100    wt. parts                                       ______________________________________                                    

Next, with the above protective layer transfer sheet superposed on theimage receiving medium having the image formed thereon in Examples asdescribed above, heating was effected with a thermal head from the sideof the heat-resistant lubricating layer to transfer the protective layeronto the dye image layer.

EXAMPLE 21

A protective layer transfer sheet was prepared in the same manner as inExample 20 except for changing the releasable protective layer, the heatseal layer to the compositions shown below.

    ______________________________________                                        Releasable protective layer                                                   (coated amount after drying: 2 g/m.sup.2)                                     Acrylic resin          20     wt. parts                                       (Mitsubishi Rayon K.K., Japan:                                                BR-85)                                                                        Polyethylene wax       1      wt. part                                        Fine particulate silica (Nippon                                                                      1      wt. part                                        Aerosil K.K., Japan:                                                          R-972)                                                                        Methyl ethyl ketone    100    wt. parts                                       Toluene                100    wt. parts                                       Heat seal layer                                                               (coated amount after drying: 1 g/m.sup.2)                                     Nylon resin (Toa Goser Kagaku                                                                        20     wt. parts                                       K.K., Japan: FS 175)                                                          Methyl ethyl ketone    100    wt. parts                                       Toluene                100    wt. parts                                       ______________________________________                                    

Next, in the same manner as in Example 20, the protective layer wastransferred onto the dye image by use of the above protective layertransfer sheet.

REFERENCE EXAMPLE 3

On the other surface of a 4.5 μm PET film having a heat-resistantlubricating layer provided on one surface was provided a polyester typeadhesion improving layer (0.1 μm), and on its upper surface was coated aprotective layer comprising one layer having the following compositionto prepare a protective layer transfer sheet.

    ______________________________________                                        Protective layer                                                              (coated amount after drying: 4 g/m.sup.2)                                     Polyvinyl butyral resin  20 wt. parts                                         (Sekisui Kagaku K.K., Japan:                                                  Ethlec BX-1)                                                                  Methyl ethyl ketone      50 wt. parts                                         Toluene                  50 wt. parts                                         ______________________________________                                    

Next, in the same manner as in Example 20, the protective layer wastransferred onto the dye image by use of the above protective layertransfer sheet.

REFERENCE EXAMPLE 4

A protective layer transfer sheet was prepared in the same manner as inExample 20 except for changing the releasable protective layer, the heatseal layer to the compositions shown below.

    ______________________________________                                        Releasable protective layer                                                   (coated amount after drying: 4 g/m.sup.2)                                     Polystyrene resin      20     wt. parts                                       (Denki Kagaku K.K., Japan:                                                    TP-SX301)                                                                     Methyl ethyl ketone    50     wt. parts                                       Toluene                50     wt. parts                                       Heat seal layer                                                               (coated amount after drying: 1 g/m.sup.2)                                     Ethylene.ethyl acrylate resin                                                                        20     wt. parts                                       (Mitsui.Du Pont Polychemical                                                  K.K., Japan: A-704)                                                           Methyl ethyl ketone    100    wt. parts                                       Toluene                100    wt. parts                                       ______________________________________                                    

Next, in the same manner as in Example 20, the protective layer wastransferred onto the dye image by use of the above protective layertransfer sheet.

REFERENCE EXAMPLE 5

In Examples 1, an image receiving medium was prepared having noprotective layer provided on the surface where the image was formed.

The dye transfer printed matters obtained as described above wereevaluated to obtain the results shown below in Table 5.

                  TABLE 5                                                         ______________________________________                                                                Abrasion                                                                      resistance                                                                      1000    3000                                               Transferability of protective layer                                                              times   times                                       ______________________________________                                        Example 20                                                                             good thermal fusion exhibited to                                                                   ⊚                                                                      ◯                                    vinyl chloride resin, with sharp                                              peel-off of protective layer                                         Example 21                                                                             good thermal fusion exhibited to                                                                   ⊚                                                                      ⊚                                 vinyl chloride resin, with sharp                                              peel-off of protective layer                                         Reference                                                                              bad heat fusion to vinyl                                                                           --      --                                      Example 3                                                                              chloride resin, and transfer                                                  could not be effected                                                Reference                                                                              heat fusion to vinyl chloride                                                                      Δ X                                       Example 4                                                                              was good, but peel-off of                                                     protective layer was bad with                                                 disturbed edge                                                       Reference                                                                              --                   X       X                                       Example 5                                                                     ______________________________________                                         *Friction resistance was measured by passing the sample through a gate        adaptability tester (Tateishi Denki: NAW 2) for 1000 times and 3000 times     and the heat transfer printing recorded matter was observed with dyes.        ⊚ neither blurring of dye image by friction nor haze of        protective layer by damage was found.                                         ◯ no blurring of dye image by friction, but slight haze of        protective layer by damage.                                                   Δ  dye image slightly blurred by friction. Also, haze of protective     layer was excessive, and image could be observed with difficulty.             X dye image blurred by friction, and observation became impossible.      

AVAILABILITY IN INDUSTRY

The image receiving medium of the present invention has excellentcharacteristics particularly as an image receiving medium in the form ofa card, and can be used widely as various information cards such asidentification certificate, driving license, membership card, etc.

We claim:
 1. A composite assembly to be thermally printed by a thermalprinting head, said assembly comprising (i) a heat transfer sheetcomprising a substrate and a dye layer formed thereon and (ii) animage-receiving medium to accept dye transferred from said heat-transfersheet, said image receiving medium comprising at least one resin sheetwhich contacts said heat transfer sheet during thermal printing, saidresin sheet including means for facilitating dye acceptance of saidresin sheet, said means comprising a polyvinyl chloride resincomposition containing 0.1 to 10 parts by weight of a plasticizer basedon 100 parts by weight of the polyvinyl chloride resin.
 2. The compositearticle according to claim 1, wherein said polyvinyl chloride resincomposition further comprises 0.1 to 5 arts by weight of a lubricantbased on 100 parts by weight of the polyvinyl chloride resin.
 3. Thecomposite article of claim 1, wherein said at least one resin sheetcontains no pigment.
 4. The composite article of claim 1, wherein saidimage receiving medium comprises a three-layer laminate structure havingoversheets comprising said polyvinyl chloride resin compositionlaminated on both sides of a center core layer comprising a rigidpolyvinyl chloride resin.
 5. The composite article of claim 1, wherein asoftening temperature of said polyvinyl chloride resin composition iswithin a range of from 50° to 70° C., according to the standardJIS-K-6734.
 6. The composite article of claim 4, further comprisingprinted information between said center core layer and said oversheets.7. The composite article of claim 4, wherein said center core layercomprises a white rigid polyvinyl chloride resin, and said polyvinylchloride composition of said oversheets is substantially transparent. 8.The composite article of claim 1, wherein said image receiving medium isin card form.
 9. The composite article of claim 1, wherein said imagereceiving medium has a surface resistance value of 10⁸ to 10¹² Ω.
 10. Amethod of forming an image by heat transfer printing, comprising thesteps of:providing (a) a sublimation heat transfer sheet including a dyelayer, (b) a fusion heat transfer sheet, and (c) an imaging receivingmedium comprising at least one resin sheet which contacts said heattransfer sheet during heat transfer printing, said resin sheet includingmeans for facilitating dye acceptance of said resin sheet, said meanscomprising a polyvinyl chloride resin composition containing 0.1 to 10parts by weight of a plasticizer based on 100 parts by weight of saidpolyvinyl chloride resin; performing sublimation heat transfer printingon a printing surface of said image receiving medium by means of (a)said sublimation heat transfer sheet and (c) said image receivingmedium; and performing fusion heat transfer printing on said printingsurface of said image receiving medium by means of (b) said fusion heattransfer sheet and (c) said image receiving medium; wherein saidsublimation and fusion heat transfer printing are conducted incombination on the same image receiving medium.
 11. The method of claim10, wherein gradation images of yellow, magenta and cyan are formed bysaid sublimation heat transfer printing, and a monotonous image of blackis formed by said fusion heat transfer printing.
 12. A heat transferprinted article obtained by heat transfer printing comprising the stepsof:providing (a) a sublimation heat transfer sheet including a dyelayer, (b) a fusion heat transfer sheet, and (c) an image receivingmedium comprising at least one resin sheet which contacts said heattransfer sheet during heat transfer printing, said resin sheet includingmeans for facilitating dye acceptance of said resin sheet, said meanscomprising a polyvinyl chloride resin composition containing 0.1 to 10parts by weight of a plasticizer based on 100 parts by weight of saidpolyvinyl chloride resin; performing sublimation heat transfer printingon a printing surface of said image receiving medium by means of (a)said sublimation heat transfer sheet and (c) said image receivingmedium; and performing fusion heat transfer printing on said printingsurface of said image receiving medium by means of (b) said fusion heattransfer sheet and (c) said image receiving medium; wherein saidsublimation heat transfer printing and said fusion heat transferprinting are conducted in combination on the same image receivingmedium.
 13. The article of claim 12, further comprising laminating aprotective layer on said printing surface after performing saidsublimation and said fusion heat transfer printing.
 14. The article ofclaim 13, wherein said protective layer comprises a heat seal layercomprising a resin fusible onto said printing surface by application ofheat, and a releasable protective layer formed on said heat seal layer.15. The article of claim 14, wherein said releasable protective layercomprises at least one material selected from the group consisting offine particles of lubricant, fine particles of substantially transparentorganic matter, and fine particles of substantially transparentinorganic matter.
 16. The article of claim 12, wherein said printingsurface of said image receiving medium contains embossed informationformed thereon.
 17. The article of claim 14, wherein said heat seallayer comprises at least one material selected from the group consistingof vinyl chloride.vinyl acetate copolymers, acryl.vinyl chloride.vinylacetate copolymers, acrylic resins and polyamide resins.
 18. The articleof claim 14, wherein said releasable protective layer comprises at leastone material selected from the group consisting of acrylic resins,modified cellulose resins, silicone resins and fluorine resins.
 19. Thearticle of claim 12, wherein said image receiving medium includes amagnetic recording layer.
 20. The article of claim 12, wherein saidimage receiving medium includes an IC memory layer.
 21. The article ofclaim 12, wherein said image receiving medium includes an opticalrecording layer.
 22. The article of claim 12, wherein said imagereceiving medium is in a card form.